Construction of ultra-stable and high-performance sodium-ion hybrid capacitors via CoMoO4 nanorods anode

Abstract

In recent years, researchers show great interest in electrode materials for sodium-ion hybrid capacitors (SIHCs) that combine the advantages of batteries and capacitors. And the high specific capacity transition metal oxides that can be used as anodes for SIHCs attract widespread attention. Herein, one-step facile hydrothermal synthesis of the CoMoO4 nanorods as the transition metal oxides are successfully obtained. Due to the well bear to the volume change, the SIHCs exhibit superior electrochemical performance and stability with CoMoO4 nanorods anode during charge and discharge. At a current density of 0.05 A g−1, with an expanded potential from 0 to 3.0 V, the specific capacitance and the high energy density of CoMoO4//AC are 37.2 F g−1 and 63.3 Wh kg−1, respectively. Meanwhile, the stability of the CoMoO4//AC in the long cycle is as expected. After 6000 cycles, the capacity retention of the CoMoO4//AC SIHC is 90% while the coulombic efficiency is always around 99%.